So, let's move on to pneumothorax.
This is a finding that you really don't want to miss because if it's large,
it needs immediate intervention,
so let's take a look at some of the imaging findings.
A pneumothorax is entrance of air into the pleural space
which causes the lung to collapse, the parietal
and the visceral pleura separate when this happens.
So, a pneumothorax results in a thin white line
which represents the visceral pleura.
You have complete absence of lung markings peripheral
to the visceral line and this is most often seen at the apex
on an upright radiograph because the air rises up towards the apex.
Pneumothoraces can actually be very difficult to see
and you have to train your eye to looking at these.
So let's take a look at a few examples
and then feel free to pause and take a good look at these
so that you can just train your eye to visualizing these.
In the supine position, air actually travels to the non-dependent portion
of the lung and collects laterally and anteriorly in the pleural space.
The pneumothorax is less likely to be seen at the apex
on a supine film because again, air is gravity dependent.
So this results in what's called the deep sulcus sign
which is a lucency inferiorly
which displaces the ipsilateral costophrenic angle
and you can see that here on the left,
with a large lucency in the left lower costophrenic angle.
So, how about on a CT?
Air is usually seen anteriorly on a CT.
Again, because it's gravity dependent and the patient is lying supine.
A CT is actually much more sensitive,
especially for the evaluation of a very small pneumothorax.
And you can see here a normal right lung
and in the left you actually have multiple cavitary lesions,
possibly an area of consolidation likely representing a pneumonia.
And then, a relatively large pneumothorax or absence of lung anteriorly.
Some common causes of pneumothorax include trauma
which can be caused by something like a rib fracture,
they can occur spontaneously, often occurring in tall thin young males.
They can be Iatrogenic which may follow as something like a lung biopsy.
They can be the result of asthma or rupture of an alveolus or a bleb,
or they could be a result of COPD or cystic fibrosis,
again because of rupture of an alveolus or a bleb.
Let's take a look at this patient here.
Do you see a pneumothorax on this film?
So, the green lines point to the visceral pleural line.
This patient does have a pneumothorax on the right.
And how about this patient, do you see anything abnormal in this patient?
Which side is the abnormality and let's start from there?
Here's a more zoomed in image of the right lung.
The abnormality is on the right.
Alright, so this patient actually has a pneumothorax.
You can see the visceral line pointed out by the white arrows.
Can you tell what the cause of this pneumothorax is?
So this is actually a hydropneumothorax.
So the air is pointed out by the blue arrow
and there's also fluid in the pleural space
which is pointed out by the white arrow.
So the pleural space can accumulate both air and fluid,
a normal pleural effusion is also located within the pleural space.
When you have a combination of both air and fluid,
this is called a hydropneumothorax.
In this patient, the pneumothorax is actually caused by a rib fracture
which you can see by the circle and that indicates
that this fluid is likely blood which you can call a hemopneumothorax.
So let's take a look at this patient here, which side is the abnormality on?
So, this is an example of a tension pneumothorax,
the abnormality is on the left, and you can see that there is shift
of the mediastinal structures away from the side of the pneumothorax,
this can actually result in hemodynamic collapse
and this is one of the findings that you really don't want to miss.
This patient needs an urgent decompression with a chest tube,
oftentimes, this decompression is performed right at the emergency room
as soon as we've diagnosed this.